A team of 20 police and SES volunteers have been combing the Warwick reach of the Condamine River on foot and by boat for signs of the 55-year-old woman who was last seen at her unit in the southern Queensland town on July 3.

Police divers joined the search yesterday.

Her disappearance is being treated as a missing persons investigation, but police said they have considered foul play.

The missing persons cases are unrelated.

Anyone with information is asked to contact Crime Stoppers on 1800 333 000.